Purification and characterization of Clostridium perfringens delta-toxin

Delta-toxin, an extracellular hemolysin released by Clostridium perfringens type C, was purified from culture supernatant fluid by sequential ammonium sulfate precipitation, thiol-Sepharose gel chromatography, isoelectric focusing, and Sephadex G-75 gel filtration. The purified preparation had a specific activity of 320,000 hemolytic units per mg of protein and was homogeneous, as determined by immunochemical and electrophoretic tests. This toxin was characterized as a single polypeptide chain composed of 391 amino acid residues, 30% of which were hydrophobic. The molecular weight was found to be 42,000, and the isoelectric point was pH 9.1. Delta-toxin appeared to be amphiphilic by charge shift electrophoresis in a three-detergent system. It was immunogenic in rabbits and lethal to mice at a dose of 0.12 micrograms. The lytic activity of delta-toxin was restricted to erythrocytes of even-toed ungulates (sheep, goats, and pigs). This activity was inhibited by GM2 ganglioside but not by other gangliosides, cholesterol, lecithin, or sphingomyelin.